Duotone, dichromatic, or whatever you want to call it. Inks that present on the paper with different colours have been very popular in recent years. The first of these inks that really took off were from Sailor’s Ink Studio set of inks but since then there are many from Sailor, from Troublemaker, Vinta and of course Birmingham Pen Company. Many of the dichromatic inks are based around a pink dye that separated from a blue teal or green dye. That is fundamentally the same combination there! The ink is green with a pink that separates when the ink pools and dries.